This document has evidence that the new secret MI5 "North" operations centre is located at Park 66, Pilsworth Road, Bury, Lancashire.

The document includes a press article from thel ondon Times,
reporting the existence, but not location, of an MI5 operations
center, north of London. The description of the building was leaked
by the building firm in a publicity brochure.

Using details included in this article (cost of GBP20.2 million, building completed in February 2008, described as a "high specification state-of-the-art commercial building"), our source located a deleted webpage of a construction firm, showing a case study for a building with the exact same description and called "Park 66 Bury". This page on the builder's site has now replaced by a blank page, but google cache retains this information.

Google Maps gives a result for "Park 66 Bury" and locates it on Pilsworth Road, Bury, Lancashire. That site also matches the descriptions given in the times.